Automatic boiler level controller

• US 6,666,086 B2
• Filed: 06/29/2001
• Issued: 12/23/2003
• Est. Priority Date: 06/30/2000
• Status: Expired due to Fees

• Current Assignee: Clark Reliance Corporation
• Original Assignee: Clark Reliance Corporation
• Inventors: Colman, Mark A., Lee, Thomas E.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): WILSON, KATINA M
• Application Number:
  US09/896,899
• Publication Number:
  US 20020108440A1
• Time in Patent Office: 907 Days
• Field of Search: 733/04.C, 732/90.R, 702/52, 702/100, 340/620
• US Class Current: 73/304.00C
• CPC Class Codes: F22B 37/54 De-sludging or blow-down devices F22B37/565 takes precedence
• CPC Class Codes: F22B 37/78 Adaptations or mounting of level indicators level indicators per se G01F
• CPC Class Codes: G01F 23/243 Schematic arrangements of probes combined with measuring circuits
• CPC Class Codes: G05D 9/12 characterised by the use of electric means

Abstract

An improved boiler water-level controller. According to one aspect of the present invention, a positive blowdown signal is presented to indicate to the operator that the alarm probe is in steam; performing blowdown until this indicator turns on helps ensure that the alarm probe is working properly. According to another aspect of the present invention, the controller uses a novel methodology of sensing water level using conductivity probes. An embodiment of this methodology uses the charging and discharging of a capacitor through a resistive value to sense the presence of water.

Claims

1. A water level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in water or not by reading said input port to determine if said capacitor is charged or not;

and

wherein said processor determines whether the at least one conductive level sensor is in water or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged by contact between the at least one conductive level sensor and the water or not.

2. A water level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in water or not by reading said input port to determine if said capacitor is charged or not;

wherein said processor determines whether the at least one conductive level sensor is in water or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged or not; and

wherein said processor further includes a second processor port and further wherein said processor charges said capacitor using at least said second processor port.

3. A water level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in water or not by reading said input port to determine if said capacitor is charged or not;

wherein said processor determines whether the at least one conductive level sensor is in water or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged or not;

wherein said capacitive circuit is an RC circuit; and

wherein said processor further includes a second processor port and further wherein said processor charges said capacitor using said second processor port.

4. A fluid level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in fluid or not by reading said input port to determine if said capacitor is charged or not;

and

wherein said processor determines whether the at least one conductive level sensor is in fluid or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged by contact between the at least one conductive level sensor and the fluid or not.

5. A fluid level system, accepting input from at least one conductive level sensor and comprising a processor having at least one input port accepting input from the at least one conductive level sensor via a capacitive circuit including at least one capacitor, said processor determining whether the at least one conductive level sensor is in fluid or not by reading said input port to determine if said capacitor is charged or not;

wherein said processor determines whether the at least one conductive level sensor is in fluid or not by causing said capacitor to be charged and by then reading said input port to determine if said capacitor has been discharged or not; and

wherein said processor further includes a second processor port and further wherein said processor charges said capacitor using at least said second processor port.

6. A water level system, accepting input from at least one conductive level sensor and comprising:

(a) a processor having at least one driver port and at least one sensing I/O port; and

(b) a capacitive circuit connected to said at least one driver port and said at least one sensing I/O port and accepting input from the at least one conductive level sensor, said capacitive circuit having at least one capacitor; and

(c) wherein said processor executes a software routine for determining whether the at least one conductive level sensor is in water or not, comprising the following steps;

i. making the at least one sensing I/O port an output and setting its output HIGH;

ii. setting the output of said at least one driver port HIGH;

iii. making the at least one sensing I/O port an input;

iv. setting the output of said at least one driver port LOW;

v. reading the least one sensing I/O port input;

vi. if the at least one sensing I/O port is at a first logical level, determining that the at least one conductive level sensor is in water; and

vii. if the at least one sensing I/O port is at a second, different logical level, determining that the at least one conductive level sensor is not in water.

7. A water level system according to claim 6, wherein if the at least one sensing I/O port is HIGH, determining that the at least one conductive level sensor is in water and if the at least one sensing I/O port is LOW, determining that the at least one conductive level sensor is not in water.

8. A water level system according to claim 6 wherein said capacitive circuit is an RC circuit.

9. A fluid level system according to claim 6, wherein if the at least one sensing I/O port is HIGH, determining that the at least one conductive level sensor is in the fluid and if the at least one sensing I/O port is LOW, determining that the at least one conductive level sensor is not in the fluid.

10. A fluid level system, accepting input from at least one conductive level sensor and comprising:

(a) a processor having at least one driver port and at least one sensing I/O port; and

(b) a capacitive circuit connected to said at least one driver port and said at least one sensing I/O port and accepting input from the at least one conductive level sensor, said capacitive circuit having at least one capacitor; and

(c) wherein said processor executes a software routine for determining whether the at least one conductive level sensor is in fluid or not, comprising the following steps;

i. making the at least one sensing I/O port an output and setting its output HIGH;

ii. setting the output of said at least one driver port HIGH;

iii. making the at least one sensing I/O port an input;

iv. setting the output of said at least one driver port LOW;

v. reading the least one sensing I/O port input;

vi. if the at least one sensing I/O port is at a first logical level, determining that the at least one conductive level sensor is in the fluid; and

vii. if the at least one sensing I/O port is at a second, different logical level, determining that the at least one conductive level sensor is not in the fluid.